Master DSA Topics - April, 2026

Practice problems across 75+ categories

All Coding Problems

Practice coding problems across all companies and topics 3600 problems | 879 Easy | 1856 Medium | 842 Hard

# Problem Difficulty Topics
661 Count Substrings That Differ by One Character Medium
Hash TableStringDynamic Programming
662 Count Substrings That Satisfy K-Constraint I Easy
StringSliding Window
663 Count Substrings That Satisfy K-Constraint II Hard
ArrayStringBinary Search
664 Count Substrings With K-Frequency Characters I Medium
Hash TableStringSliding Window
665 Count Substrings With K-Frequency Characters II Hard
Hash TableStringSliding Window
666 Count Substrings with Only One Distinct Letter Easy
MathString
667 Count Substrings Without Repeating Character Medium
Hash TableStringSliding Window
668 Count Subtrees With Max Distance Between Cities Hard
Dynamic ProgrammingBit ManipulationTree
669 Count Symmetric Integers Easy
MathEnumeration
670 Count Tested Devices After Test Operations Easy
ArraySimulationCounting
671 Count the Digits That Divide a Number Easy
Math
672 Count the Hidden Sequences Medium
ArrayPrefix Sum
673 Count the Number of Arrays with K Matching Adjacent Elements Hard
MathCombinatorics
674 Count the Number of Beautiful Subarrays Medium
ArrayHash TableBit Manipulation
675 Count the Number of Complete Components Medium
Depth-First SearchBreadth-First SearchUnion Find
Showing 661-675 of 3911
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public class MyFirstJavaProgram { Edit & Run

   /* This is my first java program.
    * This will print 'Hello, World!' as the output
    */

   public static void main(String []args) {
      System.out.println("Hello, World!"); // prints
   }
}

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